Fix #4149, fix #1199 - Store emojis as unicode (#4189)

- Use unicode when selecting emoji through picker
- Convert shortcodes to unicode when storing text input server-side
- Do not convert shortcodes in JS anymore

app/helpers/emoji_helper.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module EmojiHelper
+  EMOJI_PATTERN = /(?<=[^[:alnum:]:]|\n|^):([\w+-]+):(?=[^[:alnum:]:]|$)/x
+
+  def emojify(text)
+    return text if text.blank?
+
+    text.gsub(EMOJI_PATTERN) do |match|
+      emoji = Emoji.find_by_alias($1) # rubocop:disable Rails/DynamicFindBy,Style/PerlBackrefs
+
+      if emoji
+        emoji.raw
+      else
+        match
+      end
+    end
+  end
+end